1. Field of the Invention
This invention relates to diagnostic systems for transistor circuits.
2. Prior Art
There are known ways to detect the failure of a transistor driving an output load. For example, the circuit containing the transistor can be removed from all other circuitry and an ohm meter placed across the current path between the collector and the emitter leads to determine if the transistor is shorted. Disconnection or removal of the circuit containing the transistor can be relatively inconvenient. For example, if the transistor circuit is part of an automotive electronic engine control system, removal or disconnection of the circuit from the automobile may take an undesirable amount of time or add to the cost of any necessary repair.
Further, an additional piece of test equipment, such as an ohm meter, is necessary. An operator for the test equipment is also necessary and there may be required an interpretation of the results. The interpretation may require judgment which may lead to inconsistent diagnoses in different cases. These are some of the problems this invention overcomes.